1. How long will it take to plate 4.00 g of gold metal onto an object that is be

Question

1. How long will it take to plate 4.00 g of gold metal onto an object that is being electroplated using a 1.00 M Au3+ solution and a current of 3.00 A?

2. Gold plating of eating utensils is a way to beautify those common things that we use in everyday life. You can also think of it as a way to make something look very expensive without spending an insane amount of money (it costs less to have just the outside of the spoon made of gold instead of the whole thing). If it took 4.30 min to plate out all the gold from 500 mL of an Au3+ solution using a current of 4.0 A, what was the original concentration of the gold plating solution?

Explanation / Answer

1)

mass of gold = 4.00 g

current = 3.00 A

equivalent weight = 65.55

w = E x i x t / 96500

4.00 = 65.66 x 3.00 x t / 96500

t = 1959.6 sec

time taken = 32.66 min (or) 1.96 x 10^3 sec

2)

w = E x i x t / 96500

   = 65.66 x 4.0 x 4.30 x 60 / 96500

= 0.702 g

moles = 0.702 / 197 = 3.565 x 10^-3 mol

concentration = moles / volume (in L)

                        = 3.565 x 10^-3 / 0.5

concentration = 7.13 x 10^-3 M

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